1. Field of the Invention
The present invention relates to integrated circuits and, more particularly, to an integrated circuit and method of forming the integrated circuit that has a die with high Q inductors and capacitors that is formed on a die with a circuit as a flip chip.
2. Description of the Related Art
Low-loss, linear inductors and capacitors are common circuit elements in radio frequency (RF) applications, such as digital cellular telephones. These devices tend to be quite large with respect to the digital circuitry, and are one of the limiting factors in further significant reductions in the size of digital cellular telephones.
For example, one important measure of an inductor is the quality factor or Q of the inductor. High Q inductors are desirable in a number of RF circuits, such as resonant circuits. The Q of an inductor is given by equation (EQ.) 1 as:Q=ωL/R,  EQ. 1where ω is related to the frequency f of the signal applied to the inductor (ω=2(π)(f)), L represents the inductance of the inductor, and R represents the resistance of the inductor.
As indicated by EQ. 1, the smaller the resistance, the higher the of the inductor. One common approach to reducing the resistance of an inductor is to increase the size of the inductor. In addition, capacitors, like inductors, have a similar Q measure which increases with increasing size. As a result, high Q inductors and capacitors are often implemented at the circuit board level as discrete components, requiring a significant amount of circuit board space.
One approach to providing an integrated circuit with high Q inductors and capacitors is to fabricate both the electrical circuit and the high Q inductors and capacitors on the same semiconductor substrate. This approach, however, typically suffers from a number of drawbacks, including induced substrate currents and relatively thick metal layers.
Another approach to providing an integrated circuit with high Q inductors and capacitors that address these drawbacks is the use of micro-electromechanical systems (MEMS) technology. For example, using MEMS technology, the functionality of a low loss inductor and capacitor can be provided by using micron-sized electromechanical structures.
Although techniques exist for providing an integrated circuit with high Q inductors and capacitors, there is a continuing need for alternate structures and methods of forming the structures.